1. Field of the Invention
The present invention relates to a composite heat dissipation fan, and more particularly to a composite heat dissipation fan which can produce a multi-directional ventilating effect, thereby enhancing the heat dissipation efficiency.
2. Description of the Related Prior Art
A first conventional heat dissipation fan in accordance with the prior art shown in FIG. 1 comprises a base 90 combined with a top plate 91 which defines a wind inlet opening 92, the base 90 having a side wall defining a wind outlet opening 93. The base 90 is combined on a heat emitting member of a central processing unit. When the fan device 94 is rotated, the ambient cold air is drawn into the wind inlet opening 92 on the top of the base 90, so that the attached heat on the bottom of the base 90 combined on a heat emitting body (not shown) is carried by the drawn cold air, and is drained through the wind outlet opening 93 in the side wall of the base 90, thereby dissipating the heat. In practice, the first conventional heat dissipation fan only has a single-side sideward wind draining function, so that only one path is used to carry away the heat produced by the heat emitting body, and cannot have a multi-directional ventilating path including the downward direction and the sideward direction, thereby greatly limiting th e cooling and heat dissipation efficiency.
A second conventional heat dissipation fan in accordance with the prior art shown in FIG. 2 comprises a housing 80 combined with a stator seat 81 which is rotatably provided with an impeller 82, the housing 80 covered by a cover plate 83 which has a wind inlet opening 84 for drawing the cold air, the housing 80 having a wind outlet opening 85 and heat dissipation fins 86 having heat dissipation channels.
The impeller 82 includes upper blades 821, and lower blades 822. Therefore, when the impeller 82 is rotated, it can drive the air flow along the axial direction and along the perpendicular face of the axial center, thereby obtaining a better heat convection and dissipation effect. However, the hub of the impeller 82 has a greater diameter and area, therefore, the lengths of the upper blade 821 and lower blades 822 are limited, thereby limiting the air flow driving effect thereof.
The primary objective of the present invention is to provide a composite heat dissipation fan which produces a multi-directional ventilating effect and drives a greater air flow, thereby enhancing heat dissipation effect and efficiency.
The present invention provides a composite heat dissipation fan which includes an impeller having first blades, and the first blades having a periphery combined with second blades for creating a side directed wind supply. The impeller is provided with a magnet ring which is energized with the stator coils of the base plate, so that the impeller is induced to rotate about the rotation shaft of the base plate. The first blades draw the ambient cold air through the wind inlet opening, and the wind outlet opening of the base plate drains the wind outward. The second blades uses part of the cold air to drain wind sideward, thereby providing a multi-directional wind draining effect so as to increase the heat dissipation efficiency.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.